1. Chapter 5 Techniques in Green Chemistry

2. Chapter 5 Techniques in Green Chemistry
5.1 The performance of Catalysts in Chemical
reaction
5.2 Green Chemistry and Catalysis
5.3 The Design of High Efficient and Safe Catalyst
5.4 Changing Starting Material for Chemical
5.5 Changing Reagents
5.6 Changing the solvent of Chemical Reaction
5.7 Process Control and Process Intensification
References

3. 5.1 The performance of Catalysts in Chemical reaction

4. Samples for the Application of Catalysts
reactants
products
catalyst
T/K p/
MPa
phase
The role of catalyst 1
1/2N2＋3/2H2
NH3
Fe-K2O/Al2O3
723
40.53
Gas-solid
Accelerate reaction rate 2a
C2H4＋1/2O2
CH3CHO
PdCl2-V complex
540
0.1013
liquid
Control the Selectivity for different products

5. 左旋二羟基苯丙氨酸(L-naproxen)2b
C2H4＋1/2O2
C2 H4O
Ag/Al2O3
520
0.1013
gas-solid 2c
C2H4＋3O2
2CO2＋2H2O Ni
Gas-solid 3a
nC3H6
[C3H6]n O2
420~450
202.6
gas 3b
Cr2O3·SiO2·Al2O3
or MO3·Al2O3
3.1
Gas-solid -liquid 3c
Ziegler- Natta
373 4
2-(6-甲氧基-2萘基)丙烯酸＋氢
左旋二羟基苯丙氨酸(L-naproxen) Ru
Control the Selectivity for different products
Control the Selectivity for different products

6. 5a CH3CH2OH 623~683 Gas,solid 523 6a CH4＋O2 CO＋H2 673~1273 6b CO2＋H2O
C2H4＋H2O
Al2O3
623~683
Gas,solid
Control the Selectivity for different products 5b
（C2H5）2O
＋H2O
523 6a
CH4＋O2
CO＋H2
Ni/Al2O3
673~1273
0.1013~105
h－1) 6b
CO2＋H2O
＞673
0.1013气体时空速率~1000
h－1

7. Catalyst has been called as molecular machine
Accelerate the chemical reaction rate.
Accelerate selectively one of the several thermodynamically possible reactions and yield selectively the special products.
Namely, the use of catalysts can control the selectivity for special products.
Control the enantioselectivity of reaction.

8. Catalyst has been called as molecular machine
Synthesize the special conformation of chiral isomers:
The consideration of incorporating the catalyst with the reaction conditions could control the selectivity of chemical reaction.
High selectivity and atom economy is of the most importance in bio-process, and all the reactions in organism are catalyzed by enzyme which are characterized with high specificities, selectivity and atom economy.

9. Catalyst has been called as molecular machine
Hence, those enzyme have been called as Molecular Machine.
ADP
ATP
ATPADP+Pi
A hand-over-hand mechanism for kinesin

10. Catalyst has been called as molecular machine
Recent investigations have reported that not only enzyme acts as molecular machine but also the common catalysts own the similar functions.
The classical example is the metal cyclopentadiene (环戊二烯) complex which was used as the catalyst in olefin polymerization.

11. Ziegler-Natta catalyst: mechnsim?
齐格勒纳塔催化剂：烷基铝和三氯化钛的固体混合物
continue

13. Catalyst has been called as molecular machine
Enzyme and other traditional chemical catalyst,
If they exhibit high specificity, selectivity, yield and atom economy, they should be considered as the molecular machine with special functions in chemical reactions.

14. Chapter 5 Techniques in Green Chemistry
5.1 The performance of Catalysts in Chemical reaction
5.2 Green Chemistry and Catalysis
5.3 The Design of High Efficient and Safe Catalyst
5.4 Changing Starting Material for Chemical reaction
5.5 Changing Reagents
5.6 Changing the solvent of Chemical Reaction
5.7 Process Control and Process Intensification

15. 5.2 Green Chemistry and Catalysis

16. Catalysis and Pollution Protection
The activation of new starting materials
Catalysis and Process Promotion

17. 1、Catalysis and Pollution Protection

18. Catalysis plays an important role in pollution protection Catalysis can decrease and eliminate the release of NOx in exhaust from cars and factories，and improve the air quality.
High Temperature, NOX.
Load catalyst
Lower Temperature

19. Catalysis plays an important role in pollution protection
Catalysis can decrease the usages of volatile organic solvents Catalysis can substitute the synthetic methods and process composed of chlorine materials and intermediates, and decrease the formation of wastes.

20. Catalysis plays an important role in newly synthesize route without pollution
The chemical reaction may become more effective and more selective over catalyst, which can decrease the formation of by-products and other wastes.
Catalysts can improve the reaction conditions, such as temperature, pressure and energy consuming, and eliminate the usage of toxic reaction medium.
In short, the utilization of catalyst can satisfy the requirements of Green Chemistry.

21. 2、The activation of new starting materials

22. continue The synthesis of catechol (邻苯二酚) Traditionally:
Benzene is harmful，
Too many steps，
By-products (ketene hydroquinone)，
SO2 is not safe chemicals,
continue

23. glucose as starting martial
Draths & Frost
glucose as starting martial
Avoid the usage of toxic and harmful chemicals and sharply decrease the yield of by-products.

24. Conversion of Biomass
New Catalysts
Small Molecules
Such as: CH3COOH, CH3OH etc.
Bamboos

25. 3. Catalysis and Process Promotion

26. (1) The synthesis of acetic aldehyde
CH2=CH2
PdCl2
CuCl2水溶液
CH3CHO O2
Disadvantages:
Consume large amount of catalysts.
The concentration of Cl- is greater, and can lead to the formation of chromate by-products.
Those by-products is harmful to human healthy.
The use of Vanadium complexes led to the decreased use of PdCl2 and the decrease of aqueous Cl-, which further resulted in the reduction of the formation of Cl-containing organic compounds.

27. (2) The synthesis of hydroquinone
Traditional Method：
Disadvantage:
too many steps, a large mount of by-product, corrosive chemicals (H2SO4,HCl)

28. Environmental beigen method:
Advantages:
Greener method:
Short reaction chain，
By-products only formatted in the final step.

29. (3) The synthesis of carbonyl compounds
Varma et al: the activation under microwave and catalyst without any solvent
Cat.
Microwave
R1C(OH)R2
R1COR2
Traditionally
Organic solvent;
CrO3, KMnO4;
Salt pollution

30. Chapter 5 Techniques in Green Chemistry
5.1 The performance of Catalysts in Chemical reaction
5.2 Green Chemistry and Catalysis
5.3 The Design of High Efficient and Safe Catalyst
5.4 Changing Starting Material for Chemical reaction
5.5 Changing Reagents
5.6 Changing the solvent of Chemical Reaction
5.7 Process Control and Process Intensification

31. 5.3 The Design of High Efficient and Safe Catalyst

32. 1: Gross analysis
1. At first, analyses:
the possibility of reaction and the largest equilibrium yield,
the optimized reaction conditions,
the available materials,
atom economy of reaction in real reaction ,
economy of catalysts,
economy of catalytic reactions,
in order to evaluate the reliability of real catalysts.

33. 1: Gross analysis
2. Several factors should be considered to design parameters of catalysts.
activity, selectivity, stability, duration and toxicity, etc.
3. According to the reaction routes,
search the catalyst and possible starting materials, choose the most favorable catalysts, modify and optimize the reaction conditions.
4. Confirm the reaction possibility experimentally.
If the experiments do not confirm the theoretical perdition, the process should be re-designed.

34. 2: Design and develop the new type molecule oxygen oxidative catalysts
Traditional inorganic oxidants：
NaClO, NaBrO, HNO3, KHSO3,
CrO3,KMnO4, KCr2O7 ,etc.
The traditional inorganic oxidant can result in a large amount of:
waste salts,
hazardous gases and liquids
heavy atoms

35. Clean oxidative and their characters
The cleanest oxidative chemical
The limitation of its reaction conditions,
Often companied by other auxiliary oxidants/reductants

36. H2O2 Clean oxidative and their characters
H2O2 contain more than 47 percent active oxygen, and its oxidative products (water) is environmental benign chemical.
H2O2 is more expensive than O2 and O3, and can decompose at room temperature.

37. Clean oxidative and their characters O3：
O3 is also the environmental benign chemical oxidative, and its oxidative products is oxygen molecule. But the usage of O3 often require some special method and equipments.
transformer
O3 tube

38. Clean oxidative and their characters

39. Clean oxidative and their characters
its oxidative products is environmental benign product (N2)
the synthesis of N2O is complex and the cost of N2O is very high.

40. Clean oxidative and their characters
Lattice oxygen
In the metal oxides catalysts

41. Design of oxidative catalyst based on the reaction mechanism
The reaction mechanism of different reaction system, including catalysts，may vary.
Hence, the requirements for catalysts should also be different.
The design of catalysts should be toughly considered the reaction mechanism to meet the requirement of reaction.

42. 3: The design of new-type metal complex
catalysts
Metal complexes
Those metal-organics catalysts are widely used in homogenous catalytic reactions.
Chiral metal complexes have been used as homogenous catalyst，and can control the stereo-selectivity of the reaction.
It is very important for high stereo-selectivity to search the suitable reaction conditions, proper central metal ions and chiral groups.

43. Sample：synthesis of Naproxen
The yield of target product (S-Naproxen) reaches 97%。
2,2-二（二苯基膦）-1,1-二萘的过渡金属配合物催化剂

44. Table 5-2 Some metal complexes in industry
Chiral complesx
Indoctrination
time
RuBINAP
Amine hydrogenation
1991
chinoiline
1987（Isoquinol alkaloid）
Terpene alcohol hydrogenation
1987
Ketene hydrogenation
1911
Cu Sthiff base Complexes
1985（Cyclopropanation of olefins）
RhBINAP
hexahydrothymol
1990

45. 4: Designing of New Molecular Sieve Catalyst
Molecular sieve refers to a kind of inorganic polymer composed of aluminum silicate (silicon aluminate), bearing open structure.

46. Designing of New Molecular Sieve Catalyst
Structurally,
molecular sieve bears the tetra-XO4 structure.
one atom X shares O with other X atoms.
X may be tri-(Al, B, or Ga), tetra (Ge, Si)-, or penta-(P) valent.

47. Designing of New Molecular Sieve Catalyst
The pore diameter of molecular sieve is dependant on the number of building units, and the molecular sieve is generally named macro-, meso-, or micro-molecular sieve corresponded respectively to the mean pore diameter of >50, 2-50 or< 2 nm.

48. Designing of New Molecular Sieve CatalystX
Natural Molecular Sieve（Zeolite）is widely used in petrol refinery for its macrospore structure.
Synthesized zeolite is now commercialized and has become one of the most important catalyst in petrol industry.

49. Separation oxygen from air
变压吸附制氧

51. ZMS
碳分子筛

52. Natural Molecular Sieve（Zeolite）is also used in ion exchange process.
Designing of New Molecular Sieve Catalyst
Natural Molecular Sieve（Zeolite）is also used in ion exchange process.
Natural Molecular Sieve（Zeolite) often owns acid and base sites stimulatously.
In catalysis, molecular sieve is widely used as a new acid-base catalyst in the related reactions such as the conversion of alkanes.

53. The alkylation of butene：
Traditional method：
HF and/or H2SO4 are used as the catalysts.
Advantage: high efficiency
Disadvantages:
erosion of HF/H2SO4
production of inorganic salts
HF could be recycled, but H2SO4 could not and should be removed.

54. the use of solid molecular sieve acid catalyst：
The erosion of liquid acid is eliminated，
No inorganic salts as wastes produced.
Solid acid catalyst

55. Molecular Sieve could also be used as basic catalysts or acidic-basic bifunctional catalyst
Already used for the production of fundamental chemicals but not as widely as acid catalysts.
It will undoubtedly play an important role in the production of fine chemicals and special chemicals. For example, Cs Molecular sieve is used in the synthesis of 4-methyl-thiazoline(4-甲基噻啉，one kind of anti-fungus) instead of Cl2 or CS2 and NaOH.

56. Molecular Sieve could also be used as basic catalysts or acidic-basic bifunctional catalyst
Another example is Surface Pocket Micro-reactor.
MoMCM-22 molecular sieve is developed in the synthesis of benzene form methane.

58. O
CH2 = CH—C—NH CH2 = CH—C—NH—CH2—NH—C—CH = CH2
(Acr)
(Bis)
（聚丙烯酰胺）

59. Changing the selectivity of a chemical reaction originated from the shape of molecular sieve by chemical modification of molecular sieve
The selectivity of chemical reactions based on the shape of the molecular sieve could be altered by chemical modification of the molecular sieve, this provides wide applications of molecular sieve in controlling chemical reactions.

60. For Example
In the synthesis of 2,6-di-isopropyl naphthalene, a mixture of 2,6-, 2,7-, and 2,4-substituted naphthalene is obtained using ordinary methods.
2,6-di-isopropyl naphthalene
2,4-di-isopropyl naphthalene +
2,7-di-isopropyl naphthalene

61. For Example
The traditionally used catalyst SiO2/Al2O3 has large pores, and could not distinguish 3-substituted-isopropyl naphthalene from 4-substituted-isopropyl naphthalene, and the distinguish of 2,6-di-isopropyl naphthalene from 2,7-di-isopropyl naphthalene could neither be realized.
The separation of 2,6-di-isopropyl naphthalene and 2,7-di-isopropyl naphthalene by using special polymer liquid crystal is very troublesome and very expensive.

62. For Example
The use of molecular sieve with small pores could inhibit the formation of 3-, or 4-, substituted products but the formation of equivalent amount of 2,6- and 2,7-substituted products could not be avoided.
The formation of 3- and 4- substituted products could be eliminated, and a ratio of 2,6- to 2,7-substituted products of 7/3 could be obtained by using Zeolite-C as the catalyst.
Table 5-3 gives out the distribution of products by using different kinds of catalysts.

63. Table5-3，The distribution of the products from the alkylation of naphthalene by using different kinds of catalysts
Catalyst
Pore diameter / nm
2, 6-/2, 7-
2,6- isomer %
SiO2/Al2O3
6.0 1 32
L-molecular sieve
0.71
0.8 22
B-molecular sieve
0.73 37
C*zeolite
0.7
2.7 70
ZSM-5
0.55
Very low activity

64. Prospect for the research of molecular sieve catalysts
Molecular sieve catalysts may replace such substance as HF, H2SO4, etc., which are obviously dangerous to people’s health and the environment. Thus, molecular sieve catalyst is regarded as one kind of environmentally benign catalyst.
Simultaneously, on account of the significant increase of the activity and selectivity due to the use of molecular sieve catalyst, the research of molecular sieve catalyst will undoubtedly become one of the most prospective field in green chemistry.

65. Chapter 5 Techniques in Green Chemistry
5.1 The performance of Catalysts in Chemical reaction
5.2 Green Chemistry and Catalysis
5.3 The Design of High Efficient and Safe Catalyst
5.4 Changing Starting Material for Chemical reaction
5.5 Changing Reagents
5.6 Changing the solvent of Chemical Reaction
5.7 Process Control and Process Intensification

66. 5.4 Changing Starting Material for Chemical Reaction

67. Selection of starting materials
The feedstock has great influence on the efficiency of the synthetic routes, on the environmental effects and the healthy of human beings.
The hazard of feedstock must be considered by the producers, managers in the preservation and transportation, as well as the operators in the processing.
For some bulk chemicals, the change of feedstock may change the market, for some substance are produced just to provide certain feedstock.

68. 1. General principles for changing starting materials Reducing hazardous properties
(1). Considering the hazardous properties of the starting materials themselves
whether the substance itself is benign;
whether it poses a hazard for human beings and for the environments;
whether it poses a hazard in the form of either toxicity, accident potential, or other forms;
whether it is destructive for the ecological environment;
whether it poses other un-benign properties.

69. (2). Using preferable sources
Currently, more than 90% organic starting materials are almost exclusively derived from non-renewable carbon feedstocks, such as coal or crude oil.
Petrol-refinery is energy consuming. For example, in the U. S., the amount of energy consumed in petrol-refinery is about 15% of its energy consumption. The cost will augment for the quality of the crude oil is becoming bad.
In the production of organic chemicals from oil, oxidation reactions are usually employed, and it is well known that oxidation reactions are seriously pollutant.

70. (2) Using preferable sources
Considering the use up of oil, natural gas and coal, we must reduce our dependence on these fossil resources.
Agriculture resources and bio-resources are good alternative. Recent studies show that, many agriculture resources, such as corn, potato, soybean, and so on could be converted to textiles or nylon. Agriculture waste, biomass containing cellulose and lignin could also be converted to chemicals.

71. 2. Advantages and disadvantages of biomass as a chemical feedstock
 1. Many choices
Biomass can be broken down into a huge array of structurally diverse materials, frequently stereochemically and enantiomerically defined, giving the user a wide range of new structural features to exploit in synthesis.

72. Advantages
 2. Structural diversity available The structural complexity of the building blocks available from biomass is frequently higher when compared to building blocks derived from petrochemicals This property could lead to a reduction of reaction side products, and hence, a reduction of the amount of waste material produced in chemical processes if methodology were available to incorporate this complexity into final products.

73. Advantages  3. Already Oxygen containing
Building blocks isolated from crude oil are not oxygenated, yet many of the final products of the chemical industry are oxidized products There are few ways to add oxygen to hydrocarbons, and many of them require the use of toxic reagents (chromium, lead, etc.) in stoichiometric amounts resulting in severe waste disposal problems Biomass derived materials are often highly oxygenated.

74. Advantages  4. Prolong the lifetime of fossil resource
Increased use of biomass would extend the lifetime of the available crude oil supplies, and then make contribution to sustainable development and make sure the production of certain chemicals that could only be synthesized from oil.

75. Advantages  5. Zero CO2 emission
The use of biomass has been suggested as a way to mitigate the buildup of greenhouse CO2 in the atmosphere. Since biomass uses CO2 for growth through photosynthesis, the use of biomass as a feedstock results in no net increase in atmospheric CO2.

76. Advantages
 6. Security in materials
A chemicals industry incorporating a significant percentage of renewable materials is secure because the feedstock supplies are domestic, leading to a lessened dependence on international ‘hot spots’ .

77. Advantages  7. Flexibility Biomass is a more flexible feedstock than
crude oil. The formation and composition of crude
oil are set by geological forces.
The diversity of building blocks from biomass offers a great opportunity for the production of a range of chemicals as wide as that available from non-renewables. With the advent of genetic engineering, the tailoring of certain plants to produce high levels of specific chemicals is also possible.

78. Disadvantages
1. Many of the reported disadvantages are related to current economic circumstances.
The petrochemical industry Huge & highly efficient!
Moreover, the petrochemical industry is well established. Much of its capital investment is paid off.
The mechanisms and operation of its processes are well understood and give single products of high purity.
The biomass industry is still developing.

79. Disadvantages
2. Many of the biomass sources being considered as chemical feedstocks have traditionally been used as sources of food, and the justification for diverting part of this resource to chemical production has been questioned.
The issue becomes more acute when biomass is considered as a feedstock for fuel as well as chemical production.
Biomass also requires space to grow, and the environmental impact of large scale biomass plantations has been examined.

80. Disadvantages
Traditional sources of chemical feedstocks have been referred to as ‘three dimensional’. The presence of the third dimension allows much more feedstock to be concentrated in a smaller area.
In contrast, biomass feedstocks are ‘two dimensional’ feedstocks, and require proportionally more space for the same amount of material.

81. Disadvantages 3. Biomass is necessarily seasonal.
The crop is planted in one part of the year, and harvested in another. This leads to peaks and valleys in the supply of feedstock; yet the chemical producer planning to use biomass needs a regular day to day supply, and needs to be assured that the material used at the beginning of the year will be of the same quality as that used at the end of the year.

82. Disadvantages
4. The wide range of compositions of biomass could be a detriment especially if new processes need to be developed for each feedstock.
Moreover, the building blocks extracted from biomass are foreign to traditional chemical producers and must be demonstrated to function in a manner similar to existing building blocks without undue manipulation.

83. Chapter 5 Techniques in Green Chemistry
5.1 The performance of Catalysts in Chemical reaction
5.2 Green Chemistry and Catalysis
5.3 The Design of High Efficient and Safe Catalyst
5.4 Changing Starting Material for Chemical reaction
5.5 Changing Reagents
5.6 Changing the solvent of Chemical Reaction
5.7 Process Control and Process Intensification

84. 5.5 Changing Reagents

85. Selection of reagents
High synthetic efficiency; practicable; benign to human’s health and the environment
Many progress have been achieved in this aspect on green chemistry.
For example：
Using light instead of some reagents;
Using recoverable catalyst as it is possible;
Loading the reagents on the support to realize the reactions (using oxidative agents, reductive agents to realize the loading).

86. Selection of reagents
For example, for the oxidation of tertiary hydrocarbons to ketones, the traditional method involves the reaction of copper acetate Cu(CH3COO)2 and hydrogen peroxide (H2O2) in the aqueous solution, whereas, this reaction can also be well realized by supporting nitrate of copper onto the hydrogen peroxide impregnated K10 clay ——Cu(NO3)2/K10.

87. Chapter 5 Techniques in Green Chemistry
5.1 The performance of Catalysts in Chemical reaction
5.2 Green Chemistry and Catalysis
5.3 The Design of High Efficient and Safe Catalyst
5.4 Changing Starting Material for Chemical reaction
5.5 Changing Reagents
5.6 Changing the solvent of Chemical Reaction
5.7 Process Control and Process Intensification

88. 5.6 Changing reaction solvent
Is solvent necessary for the reaction?
5.6 Changing reaction solvent

89. Changing reaction solvent
1) Aqueous solution system
2) Ionic liquid
3) Immobilization of the solvent——
Solution of polymer
4) Solvent-free reaction
5) SCF

90. 1) Aqueous solution system
Bi-phase catalysis using water as reaction medium
Water-soluble complex compounds could be used as catalyst, and then the reaction takes place at the interface formed between the water phase and the organic phase of the reactants.

91. 1) Aqueous solution system
Micelle could be provided by varying the central atom and the ligand as well as the use of surfacants, thus the interface could be enlarged and the regional concentration of the reactants could be increased.
By varying the structure of the micelle, the stero-structure of the product could also be controlled.

93. 1) Aqueous solution system
Mild reaction conditions, high activity and selectivity could be afforded for and the separation of organic phase and water phase becomes easy.
Meanwhile, environmental pollution could be avoided.

94. 2) Ionic liquid Advantages:
1) Wide operation temperatures(-40 to 300°C);
2) High solubility to inorganic, organic and polymer compounds;
3) Behaves as Bronsted acid, Franklin acid and super-strong acid;
4) Low vapor pressure;
5) Susceptive to water or able to react with water;
6) Good thermal-stability;
7) Relative cheaper and easier to be prepared.

95. 2) Ionic liquid
Room-temperature ionic liquids are good solvents for a wide of organic , inorganic and organometallic compounds.
Typically consisting of nitrogen-containing organic cations and inorganic anions , they are easy to recycle , nonflammable , and have no detectable vapor pressure.
More recently, ionic liquids have been found to be excellent solvents for a number of chemical reactions, e. g. hydrogenation , alkylation , epoxidation , Heck-vinylation , Suzuki cross-coupling reactions and enzyme catalyzed organic reactions.

96. 3) Immobilization of the solvent——Solution of polymer
Carrying out polymerization reactions using the solvent as one of the monomer to obtain polymerized-solvent-derivates that bear the property of the solvent. Since this solvent is anchored on the polymer, thus the separation of the products from the solvent is eliminated and pollution from the volatile solvent is also eliminated.

97. The synthesis of carbonyl compounds
4) Solvent-free reaction
The synthesis of carbonyl compounds
Varma et al: the activation under microwave and catalyst without any solvent
cat.
microwave
R1C(OH)R2
R1COR2
Traditionally
Organic solvent;
CrO3, KMnO4;
Salt pollution
Solvent free!

98. 4) Solvent-free reaction
Bandger et al. combine the use of environmentally benign catalyst and microwave to synthesis 3-carbinyl-coumarin from di-methyoxybenzaldehyde and Meldrum acid without using solvent The combination of microwave and catalyst instead of solvent is effective in such processes as group protection, deprotection, oxidation, reduction, rearrangement reaction.

99. Liquid P c Critical Point Solid Pressure Vapour Temperature T c 超临界区B
超临界区
Supercritical
Region
Liquid P c C
Critical
Point
Solid
Pressure T
Vapour A
Temperature T c

100. 5) Super-critical fluent (SCF)
Transmission characters of SCF: (传递性质)
Density: Similar to liquid
Viscosity(粘度): 1/100 than liquid
Liquidity(流动性): much better than liquid
Reynolds number: much better than liquid (same current velocity)
Transfer coefficient: much better than liquid

101. Viscosity Newton Formula：μ=τyx/dμx/dy With temperature increasing,
for gas: Viscosity increases
for liquid: Viscosity decreases.
SCF:
Its viscosity is not equal to that of liquid or gas.
But it is liable to that of liquid.

102. Transfer coefficient
The transfer coefficient of SCF varies in a wide range from the value of gas and liquid, which is much dependent on the temperature and pressure.

103. Partial molar volume
In SCF，the partial molar volume of infinite dilution solute is negative.
Near the critical region, it will further become more negative (about -1000∼16000ml/mol).

104. Advantages of SCF in chemical reaction solvent
1. Phase Adjustable (Gas-like or liquid-like)
It is convenient to adjust the property of SCF from gas-like phase to liquid-like phase in term of controlling pressure.
That is to say, the control of pressure can alter the property of SCF, which makes the reaction become more effective.

105. Advantages of SCF in chemical reaction solvent
2. Density and related property adjustable
The control of pressure can adjust the density of SCF, and can also adjust other properties related with density, such as dielectric constant and viscosity, which promote the possibilities to control reaction and to increase the reactive selectivity.

106. Advantages of SCF in chemical reaction solvent
3. Gas like characteristics
SCF also own characteristics like some gases, such as low viscosity, large diffusion coefficient, which is much important to accelerate the reaction rate, especially to those reactions including gaseous reactants.

107. Sc CO2: Tc = 31.5°C, Pc = 7.37Mpa, solubility
H2O: low solubility, for separation
Other solutes (dependent on T and P)

108. Advantages of SCF in chemical reaction solvent
Another advantage of non-oxidizability for SCF CO2 makes it become an ideal reaction solvent The high concentration of CO2 in SCF CO2 make it liable to react in its SCF condition, which accelerate the reaction rate and make some reaction occur.

109. Limit for the use of scCO2 as the solvent
limit: solubility of substance in scCO2
Key:
1) introduction of co-solvent
2) phase-stabilizing agent, foaming agent;
3) chelating agent, phase-transfer agent, highly oleophylic ions (高亲油性离子)

110. Chapter 5 Techniques in Green Chemistry
5.1 The performance of Catalysts in Chemical reaction
5.2 Green Chemistry and Catalysis
5.3 The Design of High Efficient and Safe Catalyst
5.4 Changing Starting Material for Chemical reaction
5.5 Changing Reagents
5.6 Changing the solvent of Chemical Reaction
5.7 Process Control and Process Intensification

111. 5.7 Process Control and Process Intensification

112. The monitoring
and controlling of
Chemical Process
Process
intensification

113. Control the chemical reaction, make the process benign!
1. The monitoring and controlling of Chemical Process
Analytical techniques
Control the chemical reaction, make the process benign!
In situ monitor (reaction conditions such as T and P; the formation the products; etc.)
Adjusting the process parameters
(T, P, F, etc.)

114. 1. The monitoring and controlling of Chemical Process
In situ monitoring and controlling :
If small amount of a dangerous pollutant (X) will form in the process of a reaction as a side-product, and its formation is facilitated under high pressure and at high temperature, in situ monitoring of the formation of X could be applied to detect continuously the production of X, and if its concentration surpasses a certain threshold, the reaction conditions (temperature and pressure) will be changed immediately to reduce its production.

115. In situ monitoring and controlling
Other reaction parameters, such as the ratio of the feed and so on could also be controlled in situ to facilitate or inhibit the formation of certain product.

116. 2. Process intensification
includes:
development of new equipments, and
development of new technical methods.
Size of a chemical plant/volume of production: smaller
Consumption of energy: lower
By-product release: smaller
Cost: lower

117. 2. Process intensification
Definition:
Size of a chemical plant: smaller
Reaction process: cleaner
Utilization of the energy: effective
via improvement of technical equipments
via improvement of technical methods
via development of chemical equipment
via improvement of the operation unit and process

118. 2.1 Process intensification via improvement of equipment
These reductions can come from :
shrinking the size of individual pieces of equipment
cutting the number of unit operations or apparatus

119. Process intensification via development of chemical equipment
Typical examples of process intensification via development of equipment:
Spinning Disk Reactor(旋转盘反应器)
Static Mixer Reactor , abbreviated as SMR (静态混合反应器)
Static Mixing Catalysts, abbreviated as KATAPAKs
Monolithic Reactor (整体式反应器)
Microreactors (微型反应器)
Heat Exchange Reactors (热交换反应器)
Supersonic Gas/Liquid Reactor (超声波气体/液体反应器)
Jet-Impingement Reactor (射流碰撞反应器)
Rotating Packed-Bed Reactor (转动填充反应器)

120. Process intensification via improvement of the operation unit and process
Typical examples：
Static Mixers (静态混合器)
Compact Heat Exchangers （紧凑热交换器）
Microchannel Heat Exchangers（微孔热交换器）
Rotor/Stator Mixer （转子/定子混合器）
Rotating Packed Beds （转动填充床）
Centrifugal Adsorber （离心吸附器）

121. Process intensification via improvement of equipment
Monolithic Catalyst
Static Mixer Reactor
Microreactors
Process intensification via improvement of technical methods
Multifunction rector
Membrane reactor
Integration of separation techniques
Alternative energy sources

122. （1）Static-mixer-reactor (SMR)

123. （1）Static-mixer-reactor (SMR)
The technology of stirring has been greatly intensified during the last 30 years.
Surprisingly, this was achieved not by improving mechanical mixer but quite the opposite by abandoning them — in favor of static mixer.
These devices are fine examples of process-intensifying equipment.
They offer a more size- and energy-efficient method for mixing or contact fluid.

124. static-mixer-reactor (SMR)

125. Sulzer SMR static-mixer-reactor, which has mixing elements made of heat-transfer tubes, can successfully be applied in processes in which simultaneous mixing and intensive heat removal or supply are necessary, such as in nitration or neutralization reactions.

126. Sulzer SMR static-mixer-reactor
One of the more important disadvantages of static-mixing-reactor is their relatively high sensitivity to clogging by solids. Therefore, their utility for reactions involving slurry catalysts is limited.
Sulzer solved this problem (at least partially) by developing structured packing that has good static-mixing properties and that simultaneously can be used as the support for catalytic material.

127. Customer advantages Excellent plug flow behaviors and narrow residence time; No hot spots and no dead zones; High flexibility with regard to operation; Fast product transition and fast change of process conditions; Safety and environmental friendliness inherent to the design; No rotating parts thus minimal maintenance costs.

128. (2). Monolithic catalyst
Materials used in the preparation of monolithic catalysts:
Metallic or Non-metallic substrates
Which could provide a multitude of straight narrow channels of defined uniform cross-sectional shapes.
To ensure sufficient porosity and enhance the catalytically active surface, the inner walls of the monolithic channels are usually covered with a thin layer of washcoat, which acts as the support for the catalytically active species.

130. The characteristics of monolithic catalysts
very low pressure drop in the single and two phase flow, one to two orders of magnitude lower than that of conventional packed systems;
high geometrical areas per reactor volume, typically times more than in the reactors with particulate catalysts;
high catalytic efficiency, practically 100% due to very short diffusion paths in the thin washcoat layer;
exceptionally good performance in processes in which selectivity is hampered by mass-transfer.

131. Current Application of Monoliths
A well known application of monoliths is the three-way catalyst in automobiles.
The monolithic reactor can be placed directly into the exhaust pipe of the automobile without affecting the performance of the engine.
It converts hydrocarbons, carbon monoxide and nitrogen oxides to harmless products (carbon dioxide, water and nitrogen).

132. The disadvantages of monolithic reactors:
Monolithic channels are fully separated from each other and, therefore, the only heat transport mechanism is the conductivity through the monolith material, resulting in difficult for heat removing or providing.
This difficult could be overcome by washcoating or by introducing catalytically active elements.

133. (3). Micro-reactors
Micro-reactors are chemical reactors of extremely small dimensions that usually have a sandwich-like structure consisting of a number of slices with micro-machined channels.
The layers perform various functions, from mixing to catalytic reaction, heat exchange, or separation.

134. Micro-reactors
Integration of these various function within a single unit is one of the most important advantages of micro-reactors. The very high heat-transfer rates achievable in micro-reactors allow for operating highly exothermic processes isothermally, which is particularly important in carry out kinetic studies.

135. Micro-reactors
Very low reaction-volume/surface area ratios make micro-reactors potentially attractive for processes involving toxic or explosive reactants.

136. Spinning disk reactor

137. 2.2 Process intensification Process intensification via improvement of technical methods
逆流反应器（Reverse-Flow Reactors）
反应蒸馏（Reactive Distillation）
反应提取（Reactive Extraction）
反应结晶（Reactive Crystallization）
色谱反应器（Chromatographic Reactors）
周期分离反应器（Periodic Separating Reactors）
膜反应器（Membrane Reactors）
反应压出（Reactive Extrusion）
反应粉碎（Reactive Comminution）

138. 燃料电池（Fuel Cells）
膜吸附（Membrane Absorption）
膜蒸馏（Membrane Distillation）
吸附蒸馏（Adsorptive Distillation）
使用离心场（Centrifugal Fields）
使用超声波（Ultrasound）
使用太阳能（Solar Energy ）
使用微波（Microwaves）
使用电场（Electric Fields）
使用等离子体技术（Plasma Technology）等技术
或多种技术的合成。

139. Process intensification via improvement of equipment
Monolithic Catalyst
Static Mixer Reactor
Microreactors
Process intensification via improvement of technical methods
Multifunction rector
Membrane reactor
Integration of separation techniques
Alternative energy sources

140. (1). Multi-functional reactors
These can be described as reactors that,
to enhance the chemical conversion taking place and to achieve a higher degree of integration,
combine at least one more function that conventionally would be performed in a separate piece of equipment.

141. For example 1: Reverse-flow reactor
To date, reverse-flow reactors have been used in three industrial processes, SO2 oxidation, total oxidation of hydrocarbons in off-gases, and NOx reduction.
It integrated the function of heat transfer and that of chemical reaction.
For exothermic processes, the periodic flow reversal in such units allows for almost perfect utilization of the heat of reaction by keeping it within the catalyst bed and, after reversion of the flow direction, using it for preheating the cold reactant gases.

142. For example 2: Reactive catalytic distillation
Reactive catalytic distillation is one of the better known examples of integrating reaction and separation and is used commercially. In this case, the multifunctional reactors is a distillation column filled with catalytically active packing.
In the column, chemicals are converted on the catalyst while reaction products are continuously separated by fractionation. The catalyst used for reactive distillation usually is incorporated into a fiberglass and wire-mesh supporting structure, which also provides liquid redistribution and disengagement of vapor.

143. b.p. 80ºC
b.p. 183ºC

145. (2). Membrane reactors
Membrane reactor is one kind of multiple function reactor integrating the function of chemical reaction and separation.
It can be used for selective in situ separation of reaction products, thus providing an advantageous equilibrium shift, enhancing the conversion of the reactants and the yield of the target products.
It also can be applied for controlled distributed feed of some of the reacting species.

146. The advantages of membrane distillation
100% rejection of macro-molecules, colloid, cells and other non-volatiles；
lower operating pressure across the membrane than in the pressure driven processes；
less membrane fouling, due to large pore size；
potentially lower operating temperatures than in conventional evaporation or distillation.

147. Practically, no large-scale industrial application of membrane reactors have been reported so far. The primary reason for this most definitely is the relatively high price of membrane units, although other factors, such as low permeability, as well as mechanical and thermal fragileness also play an important role.

148. (3). Hybrid separations
Many of the developments in this area involve integration of membranes with another separation technique.
In membrane absorption and stripping, the membrane serves as a permeable barrier between the gas and liquid phases.
Membrane distillation is the best known hybrid, and is being investigated worldwide. It basically consists of bringing volatile component of a liquid feed stream through a porous membrane as a vapor and condensing it on the other side into a permeate liquid.

149. (4). The use of alternative forms and sources of energy
Several unconventional processing techniques that rely on alternative forms and sources of energy are of importance for process intensification.

150. The use of alternative forms and sources of energy
Among other techniques, research on sono-chemistry appears to be the most advanced.
Formation of micro-bubbles in the liquid reaction medium via the action of ultra-sound waves has opened new possibilities for chemical synthesis. These cavities can be thought of as high energy micro-reactors. Their collapse creates microimplosions with very high local energy release.

151. sono-chemistry

152. The use of alternative forms and sources of energy
This may have various effects on the reacting species, from homolytic bond breakage with free radical formation, fragmentation of polymer chains by the shock wave in the liquid surrounding the collapsing bubble For solid catalyzed systems, the collapsing cavities additionally can affect the catalyst surface----this, for example, can be used for in situ catalyst cleaning/rejuvenation.

153. The use of alternative forms and sources of energy
Solar energy also may play a role in chemical processing. A novel high temperature reactor in which solar energy is absorbed by a cloud of reacting particles to supply heat directly to the reaction site has been studied.

154. The use of alternative forms and sources of energy
Microwave heating can make some organic synthesis proceed up to 1.24 times faster than by conventional techniques.

155. 参 考 文 献

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159. 第五章 作 业 什么是催化剂?为什么说催化剂在绿色化学中有十分重要的意义? 相比于传统的氧化剂，哪些是新型的绿色氧化剂？他们各有什么特点？
第五章 作 业
什么是催化剂?为什么说催化剂在绿色化学中有十分重要的意义?
相比于传统的氧化剂，哪些是新型的绿色氧化剂？他们各有什么特点？
根据绿色化学的观点，如何改变反应溶剂？各有何特点？
以萘与丙烯发生烷基化反应为例说明催化剂结构对反应选择性的巨大影响。

160. 5.简述反应原料的重要性及绿色化学对反应原料的选择原则。
6.生物质作为化工反应原料的优、缺点。
7.超临界流体与普通流体相比性质上有何特点？使用超临界流体为反应介质有何优点？
8.超临界CO2作为反应溶剂的局限性和解决方案。
9.何谓过程强化？可用哪些方法实现过程强化？
10.何谓催化反应蒸馏？简述其过程特点。